1. Field of the Invention
The present invention relates to a chip removing device of an electro-discharge machine, and more particularly to a chip removing device of an electro-discharge machine which is capable of efficiently removing chip by supplying machining oil between a discharge electrode and a workpiece.
2. Description of the Prior Art
In general electro-discharge machining, it is required to remove chip accumulated between a discharge electrode and a workpiece in order to increase an efficiency of machining. When chip and gas are not sufficiently removed during electro-discharge machining, chip accumulates between the discharge electrode and the workpiece and the machining condition is unstable, thereby resulting in a short state of a circuit driving the discharge electrode and a hunting state of a ram to which the discharge electrode is supported. As a result, machining effect is remarkably deteriorated.
Particularly, when arc occurs between the discharge electrode and the workpiece, the machining surface of workpiece may be severely damaged due to the accumulated chip, so that machining accuracy of products may be reduced.
Therefore, various chip removing devices have been developed and used which may easily eliminate chip accumulated between a discharge electrode and a workpiece during electro-discharge machining.
As an example of techniques for removing chip, there has been used an electro-discharge machining which removes chip generated from machining portion between a discharge electrode and a workpiece by spouting or sucking machining oil together with chip through a hole formed at a discharge electrode or a workpiece.
Additionally, as another example of techniques for removing chip, there has been recently used an electro-discharge machining wherein a bottom machining is utilized which forms no hole in discharge electrode or workpiece. In this case, chip between a discharge electrode and a workpiece is removed by pumping action of machining oil caused by the vertical reciprocating movement of a ram to which the discharge electrode is mounted.
However, when the workpiece is subjected to a deep electro-discharge machining which is carried our by using a discharge electrode having a large end surface, chip removing performance is rather poor, even though the ram moves up and down. This is because the gap defined between the discharge electrode and the workpiece is extremely narrow, in the deep electro-discharge machining. During the vertical reciprocating movement of the ram, chip is discharged together with the machining oil, through the gap defined between the discharge electrode and the workpiece. At this time, a part of the machining oil remains in the gap, so that a small amount of chip mixed in the remaining machining oil still remains in the gap. Upon the upward movement of the ram, furthermore, the chip tends to enter the gap again.
Particularly, since the gap between the discharge electrode and the workpiece is very narrow, resistance occurs in machining oil entering or being discharged from the gap, thereby causing flow of the machining oil through the gap to be interrupted. Of course, this problem may be solved, by increasing the upward movement stroke of the discharge electrode. Although an amount of chip contained in machining oil may diminish, by virtue of the increased upward movement stroke of the discharge electrode, it takes a long time to the electro-discharge machine, so that a machining efficiency is considerably reduced.
A chip removing device of electro-discharge machine which can solve the aforementioned problems has been also proposed. Hereinafter, the chip removing device will be described, in conjunction with FIG. 1.
In the electro-discharge machine, a workpiece W is machined by a discharge electrode T mounted on a ram, under the condition of being completely immersed in a bath which contains machining oil therein, as shown in FIG. 1 . During the process of machining the workpiece W, chip is generated at a machining portion between the discharge electrode T and the workpiece W. In order to remove the chip, the machining portion between the discharge electrode T and the workpiece W is forcibly supplied with machining oil through a nozzle 1.
However, since the machining oil being supplied through the nozzle 1 impinges against the discharge electrode T and the workpiece W, major part thereof are spattered and mixed in the machining oil in the bath. As a result, only minor part of the machining oil enters the gap formed between the discharge electrode T and the workpiece W, so that the chip is ineffectively and insufficiently discharged through the gap. Accordingly, this chip removing device still has the aforementioned problems.